Broadly speaking the priorities of the statistical core are first to provide routine statistical support for all of the projects in the program, and second to extend and develop new statistical methodology when it is appropriate for enhancing the specific aims of the projects. Routine statistical support includes assistance in study design and appropriate sample size determination data base management summarizing plotting, and analyzing data, and assistance in writing scientific papers and abstracts. Data analysis often involves fitting linear and nonlinear models to data collected repeatedly over time or dose on the same animals. This requires the use of advanced statistical core's research effort will be focused on the further development of these techniques. More specifically, the statistical core's research goal will be extend the general linear random effects model discussed be Laird and Ware (1982) and Jennrich and Schluchter (1986) to a more general repeated measures model which may be nonlinear in the random effects as well as the parameters. this area is ripe for significant progress and of importance to many of the program's projects.